Method of inhibiting evolution of hydrogen sulfide from sulfurized oil lubricants



Patented May 30, 1950 METHOD; on INHIBITING vownon OF HYDROGEN; SULFIDEFROM SULFURIZED OIL LUBRICANTS nerrrqidacrr, lzbslhifieles, cam,assigno'r to socony vacuum- Oil Company, Incorporated, New York, Y=,- acorporation of-New York No Drawings Application,OctobrZD,1945, SerialNo. 625,461

4 claims. 1,

inthe manufacture of ktrmepressuie liibri cants' for various purposes itis common practlce tostiI iuriZe the mineral oil stock ofto blend mmer n"on with'a sulfurized' an 'or fatsu'ch as laid on; sperm oil,hydfogenf'ated fats, etc.

In the step of sulfurization whi'cli is a direct addition of sulfur tothe hatedbil; more or'less hydrogen sulfide is evolved; This'iscustomarily removed by air blowing; so that thEfilflSHGGPI'Odu'ct isfree from objectionable odor.

Unfortunately, however, the reaction by which hydrogen sulfide isproduced is often notcomp l't'ed during the manufacture of the oil, but

continues during the storage "of the product. The" dd'or thus. generatednot particularly dtrimental if the Oh is used ina closedshell, as forexample a gear case, but where the product is used for metal cutting,grindingpr forming the fetid odor of hydrogen sulfide is highlyobjectionable to the operator and is the source of many complaints. p

h I have discovered that hen anoil 'sol'uble soap of a wat'erdnsoluble,heavy metal which forms a stable sulfide is add'edto the sulfurizedproduct,

preferably as a final step in its manufacture. and

after all free hydrogen sulfide has been blown off} the furtherformation of hydrogen sulfide is inhibited over extended storagep'e'riods. Apparently the inhibiting action is common to a long list'ofheavy metals, includingcadmium, cop per, cobalt, iron, lead, manganese,mercury, nickel, silver, tin, and Zinc, and is indifferent to the natureof the soaps-forming organic acid with which the metal is combined, solong as the 'soap is readily oil-soluble. For reasons of economy,

However, and also because of their somewhat greater effectiveness, I'prefer 'to use the lead, copper, and cadmium soaps, and particularlythe'naphthenates and the oleats of'these metals.

The effectiveness of these agents in inhibiting the release of freehydrogen "sulfide, with its production of an unpleasant odor, wasdemonstrated by a series of experiments in which lead naphthenate, leadoleate, copper naphthenate, copper oleate, zinc naphthenate, and thenaphthenates of chromium, nickel, manganese, cadmium, iron, and cobaltwere used as inhibiting agents; and (A) copper sulfate, (B) cadmiumchloride, and (C) mercuric chloride as indicators.

Inmaking the tests the sulfurized compounded oils were heated and blownuntil free from odor and were'then divided into the-'requisite number ofportions and the additives mixed in. The samples were then stored forvarious periods, at the end of which paper strips spotted with solutionsof the three indicators were introduced into the vapor space above theoil and allowed to remain for five minutes (in the case of Test s for 40hours). The varying sensitivities of these indicators is shown by thefollowing table:'

TABLE' '1' Sensitivity of "indicators Classification 7 Vol; Per cent HasReactions by $815115? of in Vapor More than 0.002%. 0 n .9 6

Lesslthan 0.001% Undetermined.

TABLE II M ine'raZ =0zl with 50 sulfurized lard oil '(1 5%18') [Leadmaphthenate inhibitor] Percent Storage, Period Lead added 49 Days 76Days 203 Days 329 Days 522Days i/idiu m SIight Slight.

Slight .sdo Ntmp None..- None.

fin .Lj'ln TABLE III sulfurizedlminemltloil(0.7 added S) with 6.4%sulfurized lard'oz'l (15% S) [Lead naphthenate inhibitor] Storage PeriodTrcent LeadiAddcl" n l 3 Days 1 48 Days 274 Days.

None -Strong n N511; None None. (1 T1 1 'rln dn D0; 0.1'I';.; fin dn D0Mineral oil wit h;% or sulfurized mineral oiZ (8% added :8)

[Head naphthenate inhibitor] StoragePeriod Percent LeadAddd 84Da'yszonna s None Strong -Strong: 0.08..- m NnnP- Medium. 011 do 1Slight. 0.17 None: 0 28.;. (ln 1 DOW 3 TABLE V Mineral oil with 50%sulfurized Zara, oil (15% S) Storage Period Per cent Inhibit MetalAdded95 days 213 days 406 days Lead Naphthenate 0.056 Pb Slight--- MediumStrong.

Do 0.11 Pb do Sl1ght Medium. D 0.17 Pb None None Slight. Lead Oleate0.026 Pb- Medium Strong Do--- 0.05 Pbht Do. 0.08 Pb (1 Strong.CopgerNaphthenate 0.016 Cu 0.05 Cu Strong. 0.017 Ou 0.03 Cu 0.05 Cu NoneSlight Strong. 0.016 Zn Strong Strong" 0.03 Zn Medium do 0.05 7n JinMedium Strong.

TABLE VI Mineral ml with 50% sulfurzeed lard 012 (15% S) Per CentStorage 141 Inhibitor etal Added Days Strong.

Do. Medium. Strong.

Do. Medium. Strong.

Do. Medium.

Do. Slight. None. Strong. Do.

Medium. Strong. Medium.

TABLE VII With Phosphorized and Sulfurized Oil 15 Days Storage With 10%Phosphorized and Sulfurized Oil Days Storage Percent Lead Added NoneStrong- Strong. 0.28... N None. 0.56 do Do.

The effect of these minute additions of heavy metal soaps on the extremepressure characteristics of the lubricant is immaterial. The lead soaps,when used in greater quantity, impart extreme pressure resistance, whilethe effects of the other heavy metal soaps are either favorable orneutral.

The tests summarized in Tables II-VI, inclusive, show that as regardsthe development of free hydrogen sulfide, the lead soaps and copper andcadmium naphthen ate are substantially on a parity when the dosage isproportionate to the molecular weight of the metal, being notablyeffective as deodorizers. Copper oleate and the naphthenates of otherheavy metals, for example, chromium, nickel, manganese, cadmium, iron,and cobalt are seen. to be also effective, though the reactions aresomewhat less marked. All may be useful under given circumstances. It isadditionally apparent that the particular organic acid with which any ofthe metals is combined appears to affect only the solubility of the soapin mineral oil, a characteristic which is prerequisite to functionality.

The tests shown in Table VII indicate that lead as lead naphthenateeffectively deodorizes a phosphorized and sulfurized oil, and it isbelieved that other heavy metal soaps will serve similarly.

While the above tests show that a very minute quantity of the heavymetal soap suffices to inhibit the evolution of hydrogen sulfide instorage, it will be understood that much larger quantitles of the soapmay be used if desired, up to the point, if any, at which the soapbegins to exercise a deleterious effect on the extremepressure-resisting properties of the lubricant.

It is further understood that I do not intend to be restricted either asto nominal dosage quantities of the heavy metal soaps hereinabovementioned, or as to the particular solutions thereof, but rather intendto include all such usage within the spirit of my invention and thescope of the appended claims.

I claim as my invention:

1. The method of inhibiting the evolution in storage of hydrogen sulfidefrom lubricants compounded with sulfurized oils which consists in addingto the compounded lubricant, after removal therefrom of free hydrogensulfide, an oilsoluble soap of a metal selected from the groupconsisting of lead, cadmium, copper, zinc, chromium, manganese, iron,nickel, and cobalt, in proportions of about 4 to parts by weight of saidmetal per thousand parts by weight of sulfur.

2. The method of inhibiting the evolution in storage of hydrogen sulfidefrom lubricants compounded with sulfurized oils which consists in addingto the compounded lubricant, after removal therefrom of free hydrogensulfide, an oilsoluble soap of lead in proportions of about 4 to 75parts by weight of lead per thousand parts by weight of sulfur.

3. The method of inhibiting the evolution in storage of hydrogen sulfidefrom lubricants compounded with sulfurized oils which consists in addingto the compounded lubricant, after removal therefrom of free hydrogensulfide, an oil-soluble soap of copper in proportions of about 4 to 75parts by weight of copper per thousand parts by weight of sulfur.

4. The method of inhibiting the evolution in storage of hydrogen sulfidefrom lubricants compounded with sulfurized oils which consists in addingto the compounded lubricant, after removal therefrom of free hydrogensulfide, an oilsoluble soap of cadmium in proportions of about 4 to '75parts by weight of cadmium per thousand parts by weight of sulfur.

BERT FOLDA, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 604,515 Bragg May 24, 18982,242,624 Schulz May 20, 1941 2,246,281 Zimmer June 1'7, 1941 OTHERREFERENCES The Alkaline Earth and Heavy Metal Soaps,

E'lliott (1946), pages 144, 169, 201, 213, 214, 219

and 220.

1. THE METHOD OF INHIBITING THE EVOLUTION IN STORAGE OF HYDROGEN SULFIDE FROM LUBRICANTS COMPOUNDED WITH SULFURIZED OILS WHICH CONSISTS IN ADDING TO THE COMPOUNDED LUBRICANT, AFTER REMOVAL THEREFROM OF FREE HYDROGEN SULFIDE, AN OILSOLUBLE SOAP OF A METAL SELECTED FROM THE GROUP CONSISTING OF LEAD, CADMIUM, COPPER, ZINC, CHROMIUM, MANGANESE, IRON, NICKEL, AND COBALT, IN PROPORTIONS OF ABOUT 4 TO 75 PARTS BY WEIGHT OF SAID METAL PER THOUSAND PARTS BY WEIGHT OF SULFUR. 